Thiacetazone Tablets (INN)

150 mg


For the use of a Registered Medical Practitioner or a Hospital or a Institution only.

Initial and continuation treatment phases of tuberculosis

Thiacetazone Tablets is a thio-semicarbazone derivatives, is used in low doses as a cheap substitute for PAS to act as a companion drug to INH. Chemically, thiacetazone is 4-acetamidobenzaldehyde thiosemicarbazone. The molecular formula is C10H12N4OS and the molecular weight is 236.29.


Its structural formula is :

Thiacetazone Tablets (INN)

Thiacetazone Tablets are yellow coloured, round film coated tablets.

Each film coated tablet contains :
Thiacetazone I.P. 150 mg
Excipients       q.s.

Colour : Titanium Dioxide B.P. , Tartrazine , Sunset Yellow.

Thiacetazone is bacteriostatic. It is effective against most strains of Mycobacterium tuberculosis, although sensitivity varies in different parts of the world. Thiacetazone is also bacteriostatic against Mycobacterium leprae. Resistance to thiacetazone develops when used alone. Cross-resistance can develop between thiacetazone and ethionamide or prothionamide. 

Thiacetazone is absorbed from the gastrointestinal tract and peak plasma concentrations of 1 to 2 micrograms/ml have been obtained about 4 to 5 hours after a 150 - mg dose. About 20 % of a dose is excreted unchanged in the urine. A half-life of about 12 hours has been reported. 

Thiacetazone has been used with other antimycobacterials in the initial and continuation treatment phases of tuberculosis. Thiacetazone-containing regimens are less effective than the short-course regimens recommended by WHO but are used in long-term regimens with isoniazid in some developing countries to reduce drug costs. However, thiacetazone is not generally recommended for use in HIV-positive patients because of the risk of severe adverse reactions. Thiacetazone has been used in the treatment of leprosy, but WHO now considers that such use is no longer justified. 


Administration :
Thiacetazone Tablets is administered orally.

Dosage :
In the treatment of tuberculosis, thiacetazone has been given orally in doses of 150 mg daily or 2.5 mg/kg daily. Thiacetazone may be used with isoniazid, usually in the continuation phase of some longer treatment regimens, to prevent emergence of isoniazid resistance. Thiacetazone has also been used in the initial phase in association with streptomycin and isoniazid. Daily administration is recommended as the drug is less effective when given intermittently. 

The medical considerations/contraindications included have been selected on the basis of their potential clinical significance (reasons given in parentheses where appropriate) - not necessarily inclusive (>>   = major clinical significance).

Except under special circumstances, this medication should not be used when the following medical problem exists

>> Human immunodeficiency virus (HIV) infection 
patients with HIV infection are at increased risk of severe cutaneous hypersensitivity reactions, such as Stevens-Johnson syndrome and toxic epidermal necrolysis, because of this, thiacetazone tablets are not recommended for the treatment of tuberculosis in HIV-infected patients, or patients at increased risk of HIV, if other antituberculous agents are available; if  thiacetazone or isoniazid-thiacetazone combination must be used in patients at risk of HIV infection, patients should be carefully educated about skin reactions and told to discontinue the medication promptly if any signs or symptoms of toxicity appear .

Risk-benefit should be considered when the following medical problems exist
>> Alcoholism, active or in remission or 
>> Hepatic function impairment.
In rare cases, acute hepatic failure has been reported with thiacetazone.
>> Hypersensitivity to thiacetazone.

The tablet contains “tartrazine” colour which may cause allergic reactions, including bronchial asthma.

The efficacy and toxicity of a regimen of treatment which includes thiacetazone should be determined in a community before it is used widely since there appear to be geographical differences. Thiacetazone should not be given to patients with hepatic impairment. It has also been suggested that, because thiacetazone has a low therapeutic index and is excreted mainly in the urine, it should not be given to patients with renal impairment. Treatment should be discontinued if rash or other signs of hypersensitivity occur. It should probably be avoided in HIV-positive patients because they are at increased risk of severe adverse effects.


Pregnancy : 
Thiacetazone crosses the placental barrier, Thiacetazone Tablets should be given to pregnant mothers only if the benefit overweighs the risk.

Nursing mothers : 
Since thiacetazone is excreted in human milk, caution should be exercised when this product is administer  to a nursing woman.

Paediatric Use : 
The use of Thiacetazone Tablets in children is not recommended, as its safety and effectiveness in children have not been established.

Thiacetazone may enhance the ototoxicity of streptomycin. 

Toxicity to thiacetazone usually manifests itself within first 3 months of therapy. Anorexia nausea and vomiting are the commonest symptoms. Drug fever, skin rashes and Stevens-Johnson syndrome (erythemia multiforme) appear occasionally.The serious toxic manifestations include progressive anaemia, granulocytopenia and even agranulocytosis; it also causes kidney and liver damage.

Acute overdosage  may lead to accentuation of symptoms listed under SIDE EFFECTS.

Treatment is symptomatic and supportive.

Store below 25°(77°F), protected from moisture and light.

36 months from the date of manufacture.

Thiacetazone Tablets contains Thiacetazone I.P. 150 mg. 500 tablets are packed in a jar.


For the use of a Registered Medical Practitioner or a Hospital or a Institution only.

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